I have the opposite issue: I concentrate on my job, meet all deadlines, but won’t stay a moment over my 8-hour day if I’ve finished everything in the expected time.
A few years ago, some colleagues, who regularly stayed late after work to get things finished, started bitching about the fact that I never stay late (we do a completely different job, but in the same department), but the reason they stay late is because they talk (bitch) about) their customer interactions instead of getting on with their work!
E.g. Yesterday, one woman’s conversation with one of them (discussing a technical issue) which lasted for about 20 minutes of one person’s time, had then been discussed by the original person she spoke with, plus the four others that were sitting nearby, for about 25 minutes after she left, so instead of it being a 20-minute conversation it eventually took up a further two hours and five minutes of working time! This is a common occurrence.
My current Manager is satisfied by my work (I know this because we have monthly 1-2-1’s) but a previous one (who only did performance reviews annually) thought I was letting the team down by leaving on time, until I asked if she was happy with my work, as I’d had no complaints (she agreed she was) so I pointed out that if everyone else was having to stay late to complete their work, she was either giving them too much, or they weren’t using their time efficiently. I left her to stew that observation over, and she never mentioned it again 🤣
That being said, if your colleague is working on stuff over the weekend or late at night from home, just file that knowledge away to bring up if your work ethic is ever questioned. As long as you know you are putting in the hours of effort that you’re paid for, and are getting the work done, then you have fulfilled your obligations!